From: Han Huang (hhuang@MIT.edu)
Date: Thu Feb 04 1999 - 05:49:13 MST
http://www.skypub.com/news/special/znamya.html
Up in the Sky!
It's a Bird,
It's a Plane,
It's Znamya!
By J. Kelly Beatty
Six years ago Russian space officials conducted an
orbital test of a 20-meter-wide (65-ft) reflector called Znamya, the
Russian word for banner. The spinning space mirror directed a
4-km-wide (2=-mile) spot of reflected sunlight along a swath of
Europe that lay in predawn darkness. Although much of the target area
was blanketed by clouds, a few observers reported seeing a
1-second-long flash nearly as bright as the full Moon.
Buoyed by this success, the Russians will attempt to
deploy another giant reflector, dubbed Znamya 2.5, on February
4th. With a diameter of 25 meters, this version incoporates design
improvements that should spread the aluminized 5-micron-thick plastic
sheet more evenly when it is spun out at 1= revolutions per
second. Furthermore, Mir cosmonauts Gennady Padalka and Sergei Avdeyev
will orient the reflector by remote control, keeping it trained on
ground targets for one or two minutes at a time.
If all this works as planned, during the 16-hour test
several cities in North America and Europe could find themselves
briefly bathed in artificial light 5-10 times brighter than the full
Moon in the hours after sundown. Observers far outside Znamya 2.5's
directed beam will see the spacecraft outshining virtually every star
as it coasts across the sky in an orbit 360 km (225 miles) high. The
spacecraft should be separated by a few hundred meters, which means
they should look like a dazzling "double star? when viewed through
binoculars.
The following timetable was supplied by the Space Regatta
Consortium in Moscow on January 31st. However, since then the orbit of
the Mir space station has been adjusted three times. Consequently, Sky
& Telescope believes these times may be in error by as much as 10
minutes. For example, our predictions show that Mir will pass over
Calgary from 6:21 to 6:23 p.m. local time. Therefore, we suggest that
you check our predictions for the passages of Mir and Znamya over your
location. (Click here if you are in North America and here if you are
elsewhere worldwide.) If those predictions show that the spacecraft
are passing nearly overhead any time on the evening of February 4th,
you could potentially see the flash of Znamya?s reflected light.
Znamya Timetable
4 February 1999 ( * = 5 February)
(courtesy Space Regatta Consortium)
Moscow
time
UT
(GMT)
Local
time
Event
13:04
10:04
Progress M-40
undocks from
Mir
14:34
11:34
Znamya 2.5
reflector
deploys
16:12
13:12
6:12
pm
beam on
Karaganda,
Kazakhstan
17:45
14:45
5:45
pm
beam on
Saratov, Russia
19:20
16:20
7:20
pm
beam on
Poltava,
Ukraine
20:54
17:54
6:54
pm
beam on Liege,
Belgium
20:56
17:56
6:56
pm
beam on
Frankfurt,
Germany
2:54*
23:54
5:54
pm
beam on
Winnipeg,
Manitoba
2:56*
23:56
6:56
pm
beam on Quebec
City, Quebec
4:30*
1:30*
6:30
pm
beam on
Calgary,
Alberta
4:32*
1:32*
7:32
pm
beam on Devil's
Lake, North
Dakota
5:13*
2:13*
Test ends,
reflector is
released
This cosmic klieg light is the brainchild of the Space
Regatta Consortium (SRC), a partnership involving seven Russian
aerospace management and engineering organizations. Vladimir
Syromyatnikov, SRC's general director, hopes the Znamya test will lead
to whole constellations of space mirrors orbiting 1,500 to 4,500 km
(1,000 to 3,000 mi) up. With a diameter of 200 meters (650 feet), each
satellite could beam down a disk of light as wide as a city and 100
times the Moon's brightness. Syromyatnikov imagines such spacecraft
being used to illuminate high-latitude regions of Earth in the hours
after sunset or before sunrise, ostensibly to improve the spirits and
productivity of those forced to endure long, dark winters. The
orbiting beacons might also provide emergency lighting for cities
during disasters. Syromyatnikov even envisions using SRC's solar-sail
technology to propel interplanetary spacecraft using sunlight alone or
to power orbiting observatories.
However, the prospect of an armada of giant space mirrors
hardly comes as a delight to astronomers. "We're having enough trouble
battling light sources on the ground," contends Daniel W. E. Green
(Harvard-Smithsonian Center for Astrophysics). "To have to deal with
sources from the sky is very disheartening." Some preemptive action
has already been taken by radio astronomer Woodruff T. Sullivan
(University of Washington). In his role as General Secretary of the
International Astronomical Union (IAU), Johannes Andersen (Univ. of
Copenhagen) is trying to persuade the United Nations to recognize the
night sky as an important part of Earth's environment and to protect
it from encroachment by artificial satellites. An international
symposium on the subject will be held in July.
All this negative reaction is not lost on SRC
officials. According to Chris Faranetta, a spokesman for SRC partner
Energia Ltd., the consortium has pledged to conduct a full
environmental-impact assessment prior to full-scale
development. Faranetta also points out that few observatories exist in
the far-northern regions that the SRC hopes to illuminate. An open
letter to astronomers on SRC's Web site (http://src.space.ru) offers
the hope that these "extremist experiments" will someday provide
scientists with "unique tools for real exploration of the farthest
corners of the universe."
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